I don't have the link handy but it appears many places in this forum and will come up with Google or Forum search. Basically you edit the approved cards txt file inside the Library>Application Support>Adobe folder.
Thanks Rick. To be honest I think I've already done that. I assume it's exactly the same process needed to get it working in Premiere. As mentioned I followed the process shown on this blog: http://nrsotw.blogspot.co.uk/2012/07/enabling-mercury-playback-engine-for.html
So I've already copied my GTX660ti card details into the cuda_supported_cards.txt file. It must have worked since Premiere is now using the MPE whereas prior to going through this process it was greyed out.
Or have I completely got the wrong end of the stick and your referring to something else? If so the link would be handy. I have looked around the Net, but the problem is I'm new to AE, so quite often as I'm reading the threads in forums a fair bit of it is going over my head.
I don't think that this will ever work. It's a whole different beast and just because it works in PPro doesn't mean it has to work elsewhere. Unless there is some way to tweak/ probe/ customize the card further e.g. with nVidia's own CUDA toolkit and coerce it this way, I doubt you will have much luck. in fact this may even require soem code in OSX itself. there clearly is a reason why on teh Mac side only so few cards are supported at all...